The present invention concerns a method and device for communicating on a network. It applies in particular to local wireless networks with centralised architecture, for which each communication is organised between a so-called base communication station, also referred to as the xe2x80x9cfixed partxe2x80x9d, and a mobile communication station, also referred to as the xe2x80x9cportable partxe2x80x9d.
An example of such a communication network is given by the telephones using the European DECT standard (xe2x80x9cDigital Enhanced Cordless Telecommunicationxe2x80x9d).
In such a local network, a base station supplies a synchronisation signal to all the mobile stations in the network. The set of stations (the base station and one or more mobile stations) which thus synchronise themselves with each other, constitutes a cell.
A particular problem with these networks is that, in the absence of a base station, there is no communication possible between the mobile stations since they are not synchronised.
The document U.S. Pat. No. 5,598,407 is known, which describes a local wireless network using the European DECT standard. The network consists there of a fixed base station and mobile stations. In the absence of a central station, no communication is possible between the mobile stations present in the network.
The document U.S. Pat. No. 5,551,066 is also known, which describes a local wireless network in which the master node can be changed dynamically. In this system, all the nodes are equal and the master node remains the master definitively once it has been chosen.
The present invention aims to remedy this drawback by enabling a mobile station, in the absence of a base station, to fulfill the role of base station. Thus a network can be established even in the absence of a permanent base station.
Another aim of the invention is to make it possible to establish a local wireless network dynamically in the absence of a base station.
To this end, the present invention relates, according to a first aspect, to a method of communicating between communication stations adapted to communicate with each other when at least one of said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying a control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it includes, performed by at least one communication station initially functioning in base station mode:
an operation of determining the presence of a station functioning in mobile station mode, and
when, during the presence determination operation it is determined that no station is functioning in mobile station mode, an operation of switching into mobile station mode, during which said station goes into mobile station mode.
By virtue of these provisions, when a communication station which is functioning in base station mode cannot communicate with any mobile station, it switches into mobile station mode, which enables it:
on the one hand to save its energy, and
on the other hand, to enable a base station to enter into communication with it.
According to particular characteristics, in the communication method as briefly disclosed above, for at least one communication station functioning in mobile station mode:
an operation of determining the presence of a station functioning in base station mode, and
when during the presence determination operation it is determined that no station is functioning in base station mode, an operation of switching into base station mode, during which said station goes into base station mode.
By virtue of these provisions, this station can take the role of base station in order to determine whether at least one communication station functioning in mobile station mode is in a position to communicate with it.
According to particular characteristics, following the operation of switching into mobile station mode, said communication station performs:
an operation of determining the presence of a station functioning in base station mode, and
when, during the presence determination operation, it is determined that no station is functioning in base station mode, an operation of switching into base station mode, during which said station goes into base station mode.
According to other particular characteristics, between two successive operations of determining the presence of a station functioning in base station mode, the said station performs a waiting operation, during which it does not change functioning mode.
By virtue of each of these provisions, said station adopts successively the role of base station and of mobile station, which enables it to enter into contact with any communication station, whether the latter is functioning in mobile station mode or in base station mode.
According to a second aspect, the present invention relates to a device for communicating between communication stations adapted to communicate with each other when at least one of the said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying a control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it has, in at least one communication station functioning initially in base station mode, a processing means adapted:
to determine the possible presence of a station functioning in mobile station mode, and
when it has determined that no station is functioning in mobile station mode, to switch into mobile station mode.
The invention also relates to a network, a computer, a camera, a facsimile machine, a photographic apparatus, a television receiver, a printer, a scanner and an audio/video player, characterised in that they have a device as briefly disclosed above.
The invention also relates to:
a means of storing information which can be read by a computer or a microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above, and
a means of storing information which is removable, partially or totally, and which can be read by a computer or a microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above.
The preferential or particular characteristics, and the advantages, of said device, said computer, said camera, said facsimile machine, said photographic apparatus, said television receiver, said printer, said scanner, said audio/video player and said information storage means being identical to those of the method as briefly disclosed above, these advantages are not repeated here.
For a facsimile machine which has a means of communicating on a network (see communication preamble) the communication stations on this network may have to access the telephone line of the facsimile machine. To this end, these stations send many access request messages and thus take up a large amount of passband.
The invention sets out to remedy this drawback by enabling each communication station to know the state of the telephone line.
More generally, the invention concerns any interface between two networks.
To this end, according to a third aspect, the present invention relates to a method of communicating between communication stations adapted to communicate with each other when at least one of said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying any control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it includes, performed by a first communication station able to transmit facsimiles on an external line, and functioning in base station mode:
an operation of determining the occupation of said external line for facsimile transmission, and
when, during said determination operation, it is determined that said external line is occupied for facsimile transmission, a request operation during which said first communication station transmits, to a second communication station, a message representing a request to change communication station functioning in base station mode.
By virtue of these provisions, the communication station in question is always entirely available either for communications effected on the external line, or for communications internal to the DECT cell. In addition, by knowing whether or not said communication station is functioning in base station mode, each of the other communication stations of the cell can determine whether or not the external line is available. This knowledge makes it possible to avoid numerous attempts to access the external line, attempts which would be doomed to failure, until the external line is free.
According to particular characteristics, during said request operation, the message requesting a change includes an item of information representing an identity of a mobile station envisaged as a new base station.
By virtue of these provisions, the first station which requires the change of base station can determine and transmit the identity of the station envisaged as a new base station.
According to other particular characteristics, the second communication station is a communication station envisaged for functioning in base station mode following the request operation.
By virtue of these provisions, the two communication partners are the two communication stations which envisage exchanging their role in the cell. This simplifies communication and avoids interfering with the other communication stations.
According to particular characteristics, the second communication station performs, following the reception of the message representing a request to change station functioning in base station mode:
an operation of determining agreement, or not, to functioning in base station mode, and
an operation of answering the base station, during which the second communication station transmits a message representing agreement or not to function in base station mode.
By virtue of these provisions, it is the station envisaged as the future base station which determines whether or not it accepts this role. Thus, if the initial base station is only partially informed of the actual capability of the mobile station to take the role of base station, it cannot impose this change in role on the second communication station.
According to particular characteristics, in the absence of an answer from the second communication station, the first station considers that the envisaged change in base station has failed.
By virtue of these provisions, the method of the invention functions both with devices according to the present invention and with devices known in the state of the art prior to the present invention.
According to particular characteristics, following the request operation, the following are performed by the first communication station:
an operation of determining acceptance of change of station functioning in base station mode, and
when it is determined that the envisaged change is not accepted, a new request operation during which a new message representing a change of base station request is addressed to another communication station.
By virtue of these provisions, the station which requires a change in base station can make several successive attempts to achieve this objective.
According to particular characteristics, each request operation includes an operation of selecting a station which is the destination of the message requesting a change in station functioning in base station mode.
According to other particular characteristics:
the selection operation includes an operation of reading an identity of a destination station in a list of communication stations,
the selection operation includes an operation of determining the mobile station having better capabilities of becoming the new base station,
the selection operation includes an operation of determining a mobile station having a need to transmit,
the selection operation includes an operation of determining a mobile station which has already operated in base station mode.
By virtue of each of these provisions, the stations which are envisaged for functioning in base station mode can, in a preferential order which depends on the characteristics of the selection operation, be destinations of the messages representing a request to change station functioning in base station mode.
According to particular characteristics, the communication method according to the invention as briefly disterminated above includes, when the first station is functioning in mobile station mode, an operation of determining the occupation of said external line for facsimile transmission, and
when, during said determination operation, it is determined that said external line is not occupied for facsimile transmission, a request operation during which said first communication station transmits, to the communication station functioning in base station mode, a message representing a request to change communication station functioning in base station mode.
By virtue of these provisions, as soon as the external line is available, the first communication station attempts to re-become a base station, so that each is informed of the availability of the external line.
According to a fourth aspect, the present invention relates to a device for communicating between communication stations adapted to communicate with each other when at least one of said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying a control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it has a processing means adapted, in a first communication station able to transmit facsimiles on an external line, and functioning in base station mode:
to determine the occupation of said external line for facsimile transmission, and
when said external line is occupied for facsimile transmission, to switch into mobile station functioning mode.
The invention also relates to a network, a computer, a camera, a facsimile machine, a photographic apparatus, a television receiver, a printer, a scanner and an audio/video player, characterised in that they have a device as briefly disterminated above.
The invention also relates to:
an information storage means which can be read by a computer or a microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above, and
an information storage means which is partially or totally removable and can be read by a computer or microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above.
According to a fifth aspect, the present invention relates to a method of communicating between communication stations adapted to communicate with each other when at least one of said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode, and the stations not supplying a control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it includes, performed by a first communication station which needs to send information:
an operation of determining the presence of a second communication station functioning in base station mode able to convey said information, and
when, during the presence determination operation, it is determined that no second communication station is functioning in base station mode and is capable of conveying said information, a switching operation, during which said first communication station starts to function in base station mode.
By virtue of these provisions, when no base station is available, a station which needs to send information substitutes itself for the missing base station and thus effects the transmission of this information.
According to particular characteristics, when the first communication station functions in base station mode, it performs an operation of determining the completion of said communication and, when the communication of said information is completed, said first communication station performs a switching operation during which said first communication station starts to function in mobile station mode.
According to other particular characteristics, following said operation of switching into base station mode, said first communication station allows only a communication between itself and the communication station with which it is to communicate said information.
According to yet other particular characteristics, the communication method as briefly disclosed above includes, performed by said first communication station, when it is functioning in base station mode:
an operation of determining the presence of a station functioning in mobile station mode, and
when, during the presence determination operation, it is determined that no station is functioning in mobile station mode, a switching operation during which said station goes into mobile station mode.
By virtue of each of these provisions, the communication station which has substituted itself for a base station unavailable for the transmission of information returns to mobile station mode and, consequently:
saves its energy, and
enables a communication station functioning in base station mode to organise future communications on the network without being interfered with by the communication station which has switched into base station functioning mode.
According to particular characteristics, when the communication of said information is completed, said first communication station performs an operation of determining the existence of any communication in which it serves as a base station and, when no such communication exists, a switching operation during which said first communication station starts to function in mobile station mode.
By virtue of these provisions, the communication station which has switched into base station functioning mode enables other communication stations functioning in mobile station mode to communicate.
According to a sixth aspect, the present invention relates to a device for communicating between communication stations adapted to communicate with each other when at least one of said communication stations supplies a control signal, said station then functioning in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying a control signal then functioning in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it has a processing means adapted, when the first communication station of which the processing means forms part needs to send information:
to determine the presence of a second communication station functioning in base station mode able to convey said information, and
when it has determined that no second communication station is functioning in base station mode and is capable of conveying said information, of switching the functioning of said communication into base station mode.
The invention also relates to a network, a computer, a camera, a facsimile machine, a photographic apparatus, a television receiver, a printer, a scanner and an audio/video player, characterised in that they have a device as briefly disclosed above.
The invention also relates to:
an information storage means which can be read by a computer or a microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above, and
an information storage means which is partially or totally removable and can be read by a computer or microprocessor storing instructions of a computer program characterised in that it implements the method of the invention as briefly disclosed above.
In a local wireless network with centralised architecture, for example of the type using the DECT standard, the standardised procedures relating to security, such as authentication (a process allowing a DECT user or an item of DECT equipment to be positively verified as a legitimate user of a DECT service or item of equipment) and encryption (or xe2x80x9ccipheringxe2x80x9d, a process making it possible to code transmitted information so that it is comprehensible only by an entity having a deciphering key) of the data, serve solely to make secure the transfer of data on the radio link which connects a mobile station and the base station. Confidentiality is therefore not provided at base station level. This may be a particular problem where the mobile stations which are communicating with one another are visiting stations with respect to the cell to which they belong for the moment since the data they exchange can be used by a data processing system connected to the base station.
Thus, in the DECT standard (ETS 300 175 published by ETSI in October 1992), only transmissions between a mobile station and a base station are protected at radio link level in order to be secured from pirate listening in. Similarly, the patent U.S. Pat. No. 4,555,805 is known, which describes a centralised wireless communication system where only the communications on the radio link are encrypted or coded.
The present invention intends to remedy these drawbacks by proposing, when at least one of the mobile stations which has to intercommunicate confidentially is capable of switching into base station operating mode, that a cell formed from the stations concerned by the said confidential communication is created, a cell in which one of the stations operates in base station operating mode.
To that end, the present invention relates, according to a seventh aspect, to a method of communication between communication stations adapted to communicate with one another when one, at least, of the said communication stations supplies a control signal, the said station then operating in xe2x80x9cbase stationxe2x80x9d mode, and the stations not supplying a control signal then operating in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that, for the establishment of a confidential communication between, at least, two communication stations initially operating in mobile station operating mode, in contact with a so-called xe2x80x9cinitialxe2x80x9d base station, it includes:
an operation of switching, into so-called xe2x80x9cnewxe2x80x9d base station operating mode, of one of the said communication stations initially operating in mobile station operating mode, and
an operation of putting the new base station into communication with each of the communication stations concerned by the said confidential communication.
By virtue of these provisions, the initial base station does not have access to the data exchanged between the communication stations concerned by the said confidential communication. Confidentiality of the communication between the two communication stations is therefore provided. Furthermore, the invention can be implemented within the context of the DECT standard.
According to particular characteristics, at the end of the said confidential communication, the method which is the object of the invention includes an operation of switching the new base station into mobile station operating mode.
By virtue of these provisions, as soon as the confidential communication is finished, the communication stations concerned can again participate in communications with other communication stations.
According to other particular characteristics, by way of a preliminary to the operation of switching into so-called xe2x80x9cnewxe2x80x9d base station operating mode, the method which is the object of the invention includes a confidential communication request operation during which at least one communication station concerned by the said confidential communication receives, from another communication station concerned by the said confidential communication, a message representing a confidential communication request.
By virtue of these provisions, the confidential communication can be accepted by each of the communication stations concerned before being set up. This makes it possible, in the event of it being impossible to set up the said confidential communication or in the event of risks of interference caused by this setting up, to abandon or delay the said confidential communication.
According to other particular characteristics, during a selection operation, when a communication station which sends a message representing a confidential communication request is capable of switching into base station operating mode, it is chosen for switching into base station operating mode.
By virtue of these provisions, if a number of other communication stations are concerned by the said confidential communication, the passband used is minimised for the data sent by the new base station, on the one hand, and no other communication station has to switch its operating mode, which reduces the risks of failure, on the other hand.
According to other particular characteristics, during the confidential communication request operation, the message representing a confidential communication request includes an information item representing the operating mode of the station which is the destination of the said message during the said confidential communication.
By virtue of these provisions, any one of the communication stations concerned by the said confidential communication can find itself requested to take the role of new base station.
According to other particular characteristics, on reception of the said message representing a confidential communication request, when the information item representing the operating mode of the station which is the destination of this message is the base station operating mode, this destination station performs an operation of determining its capability of switching into base station operating mode and, where it has the capability of switching, an operation of transmitting an agreement to the communication station having sent the said message.
By virtue of these provisions, it is the communication station intended to become the new base station which determines whether it accepts this role.
According to an eighth aspect, the present invention relates to a communication device for communication between communication stations adapted to communicate with one another when one, at least, of the said communication stations supplies a control signal, the said station then operating in xe2x80x9cbase stationxe2x80x9d mode and the stations not supplying a control signal then operating in xe2x80x9cmobile stationxe2x80x9d mode, characterised in that it has a processing means adapted to:
determine a request for confidential communication between at least two stations initially operating in mobile station operating mode,
cause the operating mode of one of the communication stations concerned by a confidential communication to switch into base station operating mode, the said station then being referred to as the xe2x80x9cnew base stationxe2x80x9d, and
to put the new base station into communication with each of the communication stations concerned by the said confidential communication.
The invention also relates to a network, a computer, a camera, a facsimile machine, a photographic apparatus, a television, a printer, a scanner and an audio/video player, characterised in that they include a device as briefly described above.
The invention also relates to:
a means of storing information readable by a computer or a microprocessor storing instructions of a computer program, characterised in that it allows the implementation of the method of the invention as briefly described above, and
a means of storing information which is removable, partially or totally, and readable by a computer or a microprocessor storing instructions of a computer program, characterised in that it allows the implementation of the method of the invention as briefly described above.
The preferential or particular characteristics and the advantages of this device, this computer, this camera, this facsimile machine, this photographic apparatus, this television, this printer, this scanner, this audio/video player and these information storage means being identical to those of the method as briefly described above, these advantages are not repeated here.